Document Detail

Increasing the degrees of freedom in future group randomized trials: the df* approach.
MedLine Citation:
PMID:  15860766     Owner:  NLM     Status:  MEDLINE    
This article builds on the previous article by Blitstein et al. (2005), which showed how external estimates of intraclass correlation can be used to improve the precision for the analysis of an existing group randomized trial. The authors extend that work to sample size estimation and power analysis for future group-randomized trials. Often this approach will allow a smaller study than would otherwise be possible without sacrificing statistical power. Such studies are needed, for example, as pilot studies to help plan for a full-scale efficacy trial, as replication studies, or in situations in which resource constraints prohibit a larger trial. The authors discuss the circumstances under which this strategy will be most helpful and the risks associated with conducting smaller studies.
Jonathan L Blitstein; David M Murray; Peter J Hannan; William R Shadish
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Evaluation review     Volume:  29     ISSN:  0193-841X     ISO Abbreviation:  Eval Rev     Publication Date:  2005 Jun 
Date Detail:
Created Date:  2005-04-29     Completed Date:  2005-07-08     Revised Date:  2014-02-03    
Medline Journal Info:
Nlm Unique ID:  8004942     Medline TA:  Eval Rev     Country:  United States    
Other Details:
Languages:  eng     Pagination:  268-86     Citation Subset:  T    
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MeSH Terms
Meta-Analysis as Topic
Models, Statistical
Randomized Controlled Trials as Topic
Research Design / statistics & numerical data*
Corrected and Republished In:
Eval Rev. 2012 Dec;36(6):430-48   [PMID:  23640051 ]

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